Control system.



B. G. LAMME CONTROL SYSTEM.

APPLICATION FILED FEB. 25, 1914.- 1,241,523. Patented Oct. 2,1917.

3 SHEETS-SHEET 1.

B. G. LAMME.

CONTROL SYSTEM.

APPLICATION HLED FEB. 25. 1914.

1,241,523. Patented Oct. 2,1917.

3 $HEETSSHEET 2.

Po/e Change- 01/9/- /V. 2.

WITNESSES: INVENTUR ZQ MKQDFW x B" I ATTORNEY B. G. LAMME. CONTROLSYSTEM.

APPLICATION FILED FEB. 25,1914.

1,241,523. Patented ,Oct. 2, 1917.

3 SHEETS-SHEET 3.

WITNESSES:

ATTORNEY BENJAMIN G. LAMME, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR, TOWESTlINfi HOUSE ELECTRIC AND MANUFAG'lIlRZNG COMPANY, A CORPORATION OFPEN???- S'YLVANIA.

CONTROL s srrsn,

Specification of Letters Patent.

Patented-Oct. 2, '2;

Application filed February 25, 1914. Serial No. 820,817.

To all whom it may concern:

Be it known that I, BENJAMIN G. LAMML, a citizen of the United States,and a resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Control ASystems, of which the following; is a specification.

My invention relates to control systems for electric motors, and it hasspecial refer. ence to such systems as are adapted; to con trol theoperation of electric-locomotives or other vehicles which are providedwith a v plurality of polyphase alternating current motors receivingenergy through a phase] converter from a single-phase source.

I @no object of my invention is to provide a relatively simple system(if-control or" the class above indicated which is adapted to connectthe driving motors to operate ciently at-a plurality of running speedsas is desirable tor certain classes of iocornotive service, andparticularly to provide-such system which shall be so arranged that thecombined eiliciency of the phase converter and the driving motors shallbe substantially equivalent for the two higher ranges of operatingspeeds and, moreover shall be relatively high under full load conditionsfor both speed ranges by reason of the fact that the machines are workedat substantially their full load capacities and hence at high powerfactors in both instances.

,Another ob ect of my invention is to provide a mot-or control systemfor arranging A further object of my invention is to provide a controlsystem for a plurality of driving motors supplied with energy from aphase-converter, and to make provision for connecting the motors fordilferent economical operatingspeeds, and, at the same time, permittingthe employment of a relatively small capacity phase-con verter whichshall normally operate eiiiciently at substantially its full loadratingi- More specifically, an object of my invention is to provide asystem-involving a relatively smal -capacity phase-converter. and aplurality of IllOtOlS OftllG polyphase type having interconnectedwindings adapted to be connected for different numbers or poles,v

and to provide switching means'for arrangmg the motor windings andconnections for obtaining low, intermeohate and high speed operationwhereby the full loads upon the phase converter and motors for the twohighest speed connections are substantially equal.

recording to my inventiomli propose to accomplish. the above-mentionedobjects, as well as others of more or less specific character which willhereinafter appear as my in vent-ion is described.

Before attempt ng to set forth my invention, it is deemed advisable tobriefly con,-

sider the requirements of service upon tor-propelled vehicles of theclass in tion.

l'n generah for locomotive work-it is sirable to provioe least threeoperati speeds covering total speed range from one to four. Such a speedrange is particularly essential for locomotives which areiiitended. forboth freight and passenger service] The lowest speed is adapted forswitching and economical starting or" heavy trains, the termediate speedis adapted for normal operation particularly for freightservice, whilethe highest speed meets the special requirement of passenger or expressservice where the trains are comparatively light.

The normal or average torque conditions are required for theintermediate operating speed, while the lower speed should be a daptedto deliver substantially the sametorque for considerable periods duringthe acceleration of the load and, perhaps, to deliver a torquematerially in excess of the normal torque during the initial startingperiod. It is, therefore desirable that, at low and intermediate speeds,the motors shall operate under practically equivalent torque conditions.However, with light loads and the high-speed operating conditions, therequirement is for a horse-power output substantially equal to that ofthe intermediate speed, in which case the torque is about half of thatat the intermediate speed. Moreover, the requirement for constanthorsepower output at the high and intermediate speeds meets theconditions imposed by the employment of a phase converter which shall beas small as possible In Order to reduce expense, weight and space andwhich shall be operated efficiently at substantiall full load capacityduring the two big ran es of operating speeds.

y invention may best be understood by 1. reference to the accompanyingdrawmgs, m which Figure 1 is a diagrammaticyiew of a system of controlembodying my lnventlon, Fig. 2 is a similar view of a modified andpreferable form of my invention, Figs. 3, 4

I and 5 are simplified diagrams of the several main motor connectionseffected for the different operating speeds secured by the 5- term shownin Fig. 1, and Figs. 6, 7 an 8 are similar diagrams of motor connectionsfor the speeds effected by the system shown in Fi 2.

Reining to Figs. 1, 3, 4 and 5, the system shown comprises a supplycircuit 1, a transformer 2, a phase converter 3, a plurality ofdynamo-electric machines M1, M2, M3 and M4, a plurality of liquidrheostats R1, R2, R3 and R4, and a switching device 5 for arranging thecircuit connections of the dynamo-electric machines and rheostats.

conductor and be adapted to deliver singlephase alternatin currentenergy to a transformer2 to whic a phase converter 3 is connected insuch manner as to supply. threephase alternating current energy toconductors 6, 7 and 8. The converter 3 may be of any suitableconstruction, although I prefer to employ a converter similar to thatde- 40 tion, Serial No. 808,714, filed Decem Inasmuch as the phaseconverter 3 per tains only indirectly to my present invention, and asits construction and operation are not material to it, I shall notattempt to describe it further. a

The several motors M1, M2, M3 and M4 are of like construction and eachpreferably constitutes a three-phase induction motor having deltaconnected windings, although the particular arrangement of windings isnot essential. The several motors M1, M2, M3 and M4 are provided,respectively, with primary windings P1, P2, P3 and P4 and "5 withsecondary windings S1, S2, S3 and S4 which are wound for the same numberof poles, for instance, four poles.

The liquid rheostats R1, R2, R3 and R4 form no material parts of mypresent inven- 6 tion, except as they perform the function ofeliminating resistance from the secondary circuits of the motors duringthe accelerating periods, and, hence, may be of any suitableconstruction. Moreover, any type of adj ustable rheostats may beemployed.

The supply conductor 1 mav be a trolley scribed in detail in myco-pending applicaducting segments 20, 22 and 24; from the S4 of themotor M4, through the respective The switching device 5 comprises a set10 of stationary contact terminals which are adapted to engage aplurality of movable contact segments 11 to 34, inclusive, upon theposition-indicating lines a, b and c, for the purpose of connectin themotors for three operating speeds. he specific structure and arrangementof contact segments and terminals shown is onl illustrative of suitablemeans for accomplishing a desired end, and other types of switchingdevices adapted to effect the desired circuit connections may beemployed. A plurality of electrically controlled unit switches may alsobe use As the controller 5 is moved through its several positions a, b,and c, all of the motors are first connected in cascade, as shown inFig. 3, and then in two sets of cascade arrangements, as shown in Fig.4, and finally two of the motors are connected in parallel, as indicatedin Fig. 5, while the remainin two motors are idle. This. combination omotor connections is particularly adapted to meet the servicerequirements hereinbefore 9o discussed.

Inasmuch as the circuit connections are relatively simple and are soillustrated as to be readily followed, it is not deemed necessary totrace each circuit by specifying all of the contact members andconductors whichit includes, but, in lieu thereof, I shall merelydesignate the contact segments upon the controller 5 through which theseveral connections are completed. In this way, the description will notbe encumbered with unnecessary and lengthy enumerations of elementswhich do not add to the understanding of the invention.

Assuming the apparatus and circuit connections to be as shown in Fig. 1and the several rheostats R1, R2, R3 and R4 to be empty, the operationof the system is as follows: The controller 5 is first moved into itsposition (1, thereby establishing circuits from the several conductors6, '7 and 8 to the primary winding P1 of motor M1, through contactsegments 11, 12 and 13; from the secondary winding S1 of the motor M1,through the respective contact segments 14, 16 and 18 to the primarywinding P2 of motor M2; from the secondary winding S2 of the motor M2 tothe primary winding P3 of the motor M3, through therespectiveconsecondary winding S3 of the motor M3, through therespective contact segments 26, 28 and 3Q, to the primary winding P4 ofthe motor M4, and from the secondary winding contact segments 32, 33 and34, to rheostat R4. Thus, the motors are connected in cascadearrangement and are adapted forthe lowest speed and horse-power output,and

for the highest torque conditions.

If the rheostat R4 is gradually filled with a suitable electrolyte, themotors are gradually and correspondingly accelerated until the rheostatis filled, when the resistance in the secondary winding S4 of the motorM4 is entirely eliminated. Under these conditions, the first orlow-speed running condition is obtained.- The motor connections areshown in Fig. 3.

ln-order to increase the operating speed of the motors, the electrolytein the rheostat R4 is quickly discharged or the rheostat electrodes arewithdrawn from the electrolyte, in order to open-circuit the secondarywinding S4. Thereupon, the controller 5 may be moved into position b toestablish the second-speed motor connections.

. secondary winding S2 of motor M2 is con-.

nected to rheostat R2 through the respective contact segments 20, 22 and24. At the same time, energy is supplied from the con ductors 6, 7 and 8to the primary winding P3 of the motor M3 through circuits which includethe respective contact segment 21, 23 and 25, while the otherconnections of the secondary winding S3 of motor M3 and of boththeprimary winding and secondary winding SIXOf motor M4 aremaintained'as before described. Thus, two parallel sets of motors incascade arrangement are obtained.

if electrolyte be admitted into the rheostats R2 and P14 and theresistance of the respective secondary windings and S4 be eliminated,the, several sets of cascadeconnected motors will be brought up to aspeed corresponding to the conditions in which the secondary resistanceis eliminated. The motor connections are shown in Fig. 4. The motorsthen operate at-their second or intermediate running speed, which issubstantially double the first-speed condition, and the horse-poweroutput of the motors is substantially twice that of the low-speedarrangement, while the torque developed is substantially the same.

The secondary circuits of, the windings S2 and S4 may thenbeopen-circuited by discharging the electrolyte in the respectiverheostats R2 and R4, or by other suitable means, after which thecontroller5 is moved into position 0. By so doing, the connections tothe primary winding P1 of motor M1 are maintained as already described,

while the secondary winding S1 is connected to rheostat R1 throughcircuits Ii desirable, other means may employed for open-circuiting thesecondary.

including the respective contact segments 1.4, 16 and 18. Energy is alsosupplied to the primary winding P2 of motor M2 from conductors 6, 7 and8 by establishing circuits which include contact segments 15, 17 and 19,the connections of the secondary winding S2 of the motor M2 to therheostat R3 being as already set forth.

Upon the completion of the circuits just traced, the motors M1 and M2are connected in parallel, while the motors M3 and M4 are disconnectedfrom the circuit and remain idle. Electrolyte may now be admitted togradually fill the rheostats E1 and R2, thus bringing the motors M1 andM2 up to full running speed with their secondary resistances eliminatedfrom circuit.

The motor connections are shown in Fig. 5 in full lines Under theseconditions, the speed. is substantially double the intermediate speed,the torque of the motors is substantially halved, and the horse-poweroutput is approximately the same as that of? the intermediate-speedconnections.

Only" two motors M1 and M2 are employed in this higlrspeed operation forthe reason that the total horse-power output may thus be maintainedsubstantially equal to that of the four motors when connectedintermediate speed operation, while ciliciently operating the motors M1and M2 to their full capacity. Moreover, such an arrangement isparticularly desirable because it meets the service requirements and permits of the use of a phase converter of minimum capacity which is loadedto its full rating during both intermediate and high-speed full-loadoperation.

It is possible to secure the desired motor horse-power output andconverter ful -load eapacity by employing all or the motors forhigh-speed operation, but, under such conditions, the several motors M1,M2, l and M4 would only be loaded to hall? rating, which would result ina relatively lower power-factor than if they were operated at their fullcapacity.

Reference may now be had to Figs. 2, 6, 7 and 8 which illustrate thepreferable form of my invention. The system shown in these figurescomprises a supply conductor 1, a transformer 2, a phase converter 3, a

plurality of conductors or train lines 6, 7 and 8, a plurality of motorsM 1, and M 2, a plurality of switching devices marked Pole Change-over#1, Pole Change-over #2, and Cascade Switch, a plurality of rheostats R1 and R 2, a plurality of line switches 40, and 41, and a pluralityofshortcircuiting switches 42 and 43.

No description of the supply conductor 1, transformer 2, phase converter3 and rheostats R 1 and R 2 will be given, as they are of like characterto those set forth in connection with Fig. 1.

The motors M 1 and M 2 are of like construction, and the motor M 1 isprovided with a primary winding P 1 having end connections A1,, B1,, andC1 and intermediate connections A1, and B1 and C1,, while the secondarywindin S 1 is provided with end connect-ions X1 l and Z1,,, and withintermediate connections X1,, Y1, and Z1 The motors M 1 and M 2 areprovided with primary and secondary windings which are permanentlyconnected in delta and are arranged for a articular number of poles, forinstance, eig t poles, while, if the supply circuit connections are madeto the intermediate points of the windings, said windings are connectedin parallel-star and adapted for half the number of poles or four poles.

Before further describing my invention, it should be understood that, byreason of the peculiar arrangement of motor windings, whereby difi'erentnumbers of poles are produced, the full-load capacity or horse-poweroutput of the motors is maintained substantially constant, the output ofthe motors when connected for'the difi'erent number of poles differingapproximately only 15%. This relation of outputs or motor capacities isof special importance in meeting the service requirements with a phaseconverter of minimum size and capacity which shall be operated mostefiiciently.

The switching device marked Pole Change-over #1 is provided with aplurality of sets 46 and 47 of stationary contact terminals and movablecontact. segments 48 to 63, inclusive, which are adapted to makecoiiperative engagement when the switching device occupies itsrespective positions marked 8 pole and 4 pole.

The switching device marked Pole Change-over #2 is similar inconstruction to the one just described and embodies a plurality of sets66 and 67 of stationary contact terminals and coiiperating movablecontact segments 68 to 83, inclusive.

The switching device marked Cascade Switch is also of similarconstruction and comprises a plurality of sets 86 and 87 of stationarycontact terminals and cooperating movable contact segments 88 to 96,inclusive. The Cascade Switch is adapted to occupy two positions markedOfl and 4 o The Pole Change-over #1 and Pole Change-over #2 are,respectively, adapted to arrange the connections of the windings P 1 andS 1 of motor M 1 and the windings P 2, S 2 of motor M 2 for thedifferent numbers of poles, namely, eight poles and four oles, 'asassumed, while the Cascade witch has for its function to arrange themotor connections for connecting the motors either in parallel or incascade arrangement.

According to this preferred form of my invention, the motors are firstconnected in cascade with the larger number of poles, namely eight, asshown in Fig. 6, are then connected in parallel with the larger numberof poles as shown in Fig. 7, and are subsequently connected in parallelwith the smaller number of oles, namel four, as shown in Fig. 8, wherebthe esired operating speeds are secure Assuming the connections andvarious parts of the apparatus to be as shown, the operation of t 0system is as follows: The line switch 40 is first closed, therebyconnecting the conductors 6, 7 and 8 to the respective connections A1,,B1, and C1, of the motor M 1 through contact segments 48, 49 and 50 ofPole Change-over #1, while the points X1,,, Y1, and Z1, of the secondarywinding S 1 are respectively connected to points X2 Y2 and Z2 of thesecondary winding S 2 of motor M 2 through a circuit including contactsegment 56 of Pole Change-over #1 and contact segment 88 of the CascadeSwitch, another circuit including contact segment 57 of the PoleChange-over #1 and contact segment 89 of the Cascade Switch, and anothercircuit through contact segment 58 'of Pole Change-over #1 and contactsegment 90 of the Cascade Switch. The primary winding P2 of motor M 2has its points A2,, B2 and C2, connected to the rheostat R 2,respectively, through a circuit including contact segment 68 of PoleChangeover #2 and contact segment 91 of the Cascade Switch, anothercircuit including contact segment 69 of Pole Change-over #2 and contactsegment 92 'f the Cascade Switch, and another circuit including contactsegment 70 of Pole Change-over #2 and contact segment 93 of the CascadeSwitch.

- Thus, the motors M 1 and M 2 are connected in cascade relation, withtheir primary and secondary windin arranged for eight oles, it beingnoted t at motors Ml and- 2 are connected secondary-to-secondary insteadof secondary-to-primary, as is usually done. If electrolyte is admittedinto rheostat R 2, the motors are adually accelerated as the rheostat isfill ed, and the secondary resistance of the motor M 2 is eliminated.When the rheostat R 2 is filled with electrolyte, it maybeshort-circuited through the short-circuiting switch 43. The motors arethus brought up to their first running speed and are adapted to delivertheir greatest torqueand are connected for their smallest horse-poweroutputs. The motor connections are shown in Fig. 6.

The short-circuiting switch 43 will then be opened and the electrolytewill be discharged quickly from the rheostat R 2, after which theCascade Switch will be moved to The primary winding P 1 of the motor M 1v is connected to the conductors 6, 7 and 8, in

the manner already described, while the points X1 Y1, and Z1, of motor M1 are connected to rheostat R 1 through circuits,

respectively including contact segment 56,

contact segment 57 and contact segment 58 of the Pole Change-over #1.

The line switch 41 being closed, connections are established fromconductors 6,7 and 8 to points A2,, B2 and C2 of the secondary winding M2 through the respective contact segments 68, 69 and 70 of the PoleChangeover #2, while points X2 Y2 and Z2 are, respectively, connected torheostat R 2 through a circuit including contact segment 88 of theCascade Switch, contact segment 76 of Pole Change-over #2 and contactsegment 94 of the Cascade Switch, another circuit through contactsegment 89 of the Cascade Switch, contact segment 77 of Pole Change-over#2 and contact segment 95 of the Cascade Switch, and another circuitincluding contact segment 90 of the Cascade Switch, contact segment 78of the Pole Change-over #2 and contact segment 96 of the lascade Switch.The motors M 1 and M 2 are thus connected in parallel with their largestnumber of poles, as shown in Fig. 7.

The rheostats R 1 and R 2are then filled with electrolyte graduallyuntil the motors are brought up to their second or intermediate runningspeed when the rheostats are short-circuited respectively byshort-circuitin switches 42 and 43.

nder these conditions, the operating speed and full-load capacities ofthe motors are substantially double those corresponding to the low-speedconnections, while the torque thereof is maintained approximately thesame.

In order to effect the high-speed connections, the short-circuitingswitches 42 and 43 are opened and the electrolyte is discharged from therheostats R 1 and R 2. Subsequently, the Pole Change-over" switches aremoved to their four pole position for reconnecting the windings of themotors for a smaller number of poles.

Having moved the Pole Change-over switches into their four polepositions, connections are established from the conductors 6, 7 and 8 tothe intermediate points A1 B1 and C1 through the respective contactsegments 51, 53 and 55 of Pole Change-over #1, while the points A1 B1and C1 are interconnected by means of contact segments 52 and 54. Theintermediate points X1 Y1 and Z1, are connected to rheostat R 1 throughcircuits respectively including contact segment 59, contact segment 61and contact segment 63 of the Pole Change-over #1, while the points X1Y1, and Z1 are interconnected through contact segments 60 and 62.

The windings P 2 and S 2 of motor M 2 are similarly connected throughcorresponding segments of Pole Change-over #2, and, on account of thesimilarity of connections and the ease with which they may be traced, nodetailed description thereof will be given.

In this manner both motors M 1 and M 2,

with their smaller number of poles, are connected in parallel, andhence, said motors may be brought up to their high-speed operation bygradually filling the rheostats R 1 and R 2 with electrolyte, afterwhich said rheostats may be short-circuited by the short-circuitingswitches 42 and 43.

As already pointed out, the horse-power outputs of the motors underthese conditions are substantially the same as when connected for theirintermediate operating speed, while the torque developed is abouthalved. This arrangement of motor connections, therefore, fulfils theassumed service requirements and provides for efiicient motor operationwith a phase converter of minimum capacity and size. Moreover, themotors and the phase converter are operated at substantial full-loadconditions during both the hi h speed connections.

It may be desirable under certain circumstances, to employ either two orthreephase motors having a plurality of separate windings adapted fordifferent numbers of poles. For instance, the motors may be providedwith separate windings arranged for six poles and four poles, and saidmotors may be interconnected either in cascade or in parallel to givetwelve poles, ten poles, eight poles or four poles.

Although I have shown and described my invention as embodying apparatusof a more or less specific type of construction, and number of phases,and as involving particular circuit connections, it is evident that thebroad principles of my invention may be utilized by means of apparatusand circuit connections differing materially from those set forth and I,therefore, desire that only such limitations shall be imposed as areindicated in the appended claims.

I claim as my invention:

1. In a control system, the combination with a plurality of inductionmotors severally rovided with interconnected windings a apted to beconnected in delta and in parallel star with different numbers of poles,of switching apparatus for successively cascading said motors with thewindings connected in delta with the larger number of poles, forparalleling said motors with windings connected in delta with the.

same number of poles, and for paralleling said motors with windingsconnected in pafallel star with the smaller number of po es.

2. In a control system, the combination; with a plurality 'of inductionmotors sev-' establishing connections to the mid-points of the severalmotor windings and connecting said motors in parallel.

4. The method of operating a plurality of induction motors severallyprovided with a single primary and a single secondary Winding whichconsists in connecting said motors in cascade relation with the windingsof each of the motors in delta relation, changing from cascade toparallel connection of the motors, and changing to parallelstar relationof the windings of each of the motors.

5. The combination with a pair of twospeed polyphase induction motorshaving primary and secondary windings, of a switching device for eachmotor adapted in one position to connect the windings thereof for onenumber of poles and in another position to connect the windings for halfsaid number of poles, and another switching device adapted in oneposition to connect the secondary windings of said motors together for.cascade o eration with the larger 40 number of poles an in anotherposition to connect the windings of said motors for parallel operationwith the smaller number of poles.

6. The method of operating a plurality 48 of induction motors severallyprovided with interconnected windings which consists in cascading themotors with the windings connected in delta relation to. provide arelatively large number of poles, paralleling the motors with the sameinternal connections, and paralleling the motors with windings connectedin parallel-star to provide a relatively small number of poles.

7. The method of obtaining a geometricalratio series of speeds inconnection with a plurality of induction motors severally provided withinterconnected windings which consists in initially cascading the motorswith the windings connected in delta rela- 60 tion to provide apredetermined number of poles, then paralleling the motors with the sameinternal connections, and finally paralleling the motors with windingsconnected in parallel-star to provide one-half of said 65 predeterminednumber of poles.

In testimony whereof I have hereunto subscribed my name this 20th day of'Feb.,

BENJ. G. LAMIME.

Witnesses E. LIVINGSTONE, B. B. Hnms.

